Prehistoric DNA to Help Solve Human-Evolution Mysteries?

The oldest DNA ever found comes from Siberian dirt analyzed by bioarchaeologist Eske Willerslev at Oxford University in England. Willerslev, who also spoke at PITTCON, the Chicago chemistry conference, has found fragments of DNA from plants, fungi, and animals in 350,000-year-old permafrost soil cores.

But Poinar believes that, under exceptional circumstances, researchers might be able to get small fragments of DNA in human and animal bones that are up to a million years old, and protein sequences from even earlier.

Hominid DNA could then be used to piece together the much-disputed relationships of our extinct relatives.

"Sadly there's not much hope for many of the African fossils," Poinar said, pointing to the fact that most hominids are known from hot climates where DNA degrades rapidly. Cool cave sites at high elevations would be the best bet, he said.

Poinar's work centers on the analysis of coprolites: fossilized human and animal dung. Analyzing DNA from fossilized Cro-Magnon human and Neandertal feces might provide answers to questions about early human evolution, particularly the evolution of language. Poinar hopes to acquire fossil coprolites from the caves of Mount Carmel near Haifa in Israel.

Geneticists have shown that a gene called FOXP2 may be required for the fine-tuning of speech. Studies suggest that this gene may have evolved in its present version around 50,000 years ago, Poinar said.

DNA in these fossils from Israel might therefore confirm whether the modern version of the gene had evolved by that time and might hint at whether Neandertalsthe last of whom died out 40,000 years agohad the ability to speak or not.

"In theory it might be possible to extract hominid DNA from [very old] fossil bones," commented Matthew Collins, director of York University's Bioarcheology Center in England. Collins is also a speaker at the Chicago conference and part of the team that extracted protein from the 60,000-year-old bison bone.

But proteins are much more durable, Collins said. Tightly bound to bone, and permanently frozen, they might last for an astounding 100 million years. Though a very long shot, he said, it is theoretically possible that even dinosaur fossils (the youngest of which are 60 million years old) could harbor some genetic information.

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